Send a Transaction

Once the smart account is set up, sendTransaction() handles everything: it prompts the user to sign, submits the UserOperation to the bundler, and returns a response object.

All transactions go through the 0xGasless paymaster — no ETH required from the user.

Single transaction

const response = await client.sendTransaction({
  to: '0xRecipientAddress',
  value: 0n,         // Value in wei (bigint). Use 0n for contract calls.
  data: '0x',        // Encoded call data. '0x' for plain transfers.
});

console.log('UserOp hash:', response.userOpHash);

// Wait for the transaction to be mined
const receipt = await response.wait();
console.log('Tx hash:', receipt.receipt.transactionHash);

Batch transactions

Send multiple calls in a single UserOperation. This is cheaper than two separate transactions and creates a better user experience — the user signs once, not twice.

const response = await client.sendBatchTransactions([
  {
    to: '0xContractA',
    value: 0n,
    data: encodedCallA,
  },
  {
    to: '0xContractB',
    value: 0n,
    data: encodedCallB,
  },
]);

Transaction parameters

Field	Type	Required	Description
to	0x${string}	Yes	Recipient address or contract address.
value	bigint	No	ETH value in wei. Defaults to 0n.
data	0x${string}	No	ABI-encoded call data. Defaults to '0x'.

Waiting for confirmation

response.wait() polls until the transaction is included in a block:

const { userOpHash } = await client.sendTransaction(tx);

// Wait and get the full receipt
const receipt = await response.wait();
if (receipt.success === 'true') {
  console.log('Confirmed in tx:', receipt.receipt.transactionHash);
}

Or just get the transaction hash as soon as it’s known, without waiting for mining:

const { transactionHash } = await response.waitForTxHash();
console.log('Hash:', transactionHash);

Encoding contract calls

Use viem’s encodeFunctionData to build the data field:

import { encodeFunctionData, parseAbi } from 'viem';

const data = encodeFunctionData({
  abi: parseAbi(['function mint(address to)']),
  functionName: 'mint',
  args: [client.smartAccountAddress],
});

await client.sendTransaction({
  to: '0xNFTContractAddress',
  value: 0n,
  data,
});

Error handling

try {
  const response = await client.sendTransaction({ to: '0x...', value: 0n });
} catch (err) {
  if (err instanceof Error) {
    console.error('Transaction failed:', err.message);
  }
}